Technical Field
The disclosure relates to a display device, and in particular it relates to a channel layer composition of a thin film transistor of the display device.
Description of the Related Art
Displays mainly include thin film transistors and other electronic elements. In the structure of a thin film transistor, the general material of the semiconductor layer is amorphous silicon (a-Si). However, the material of the semiconductor layer gradually changes to metal oxide, especially indium gallium zinc oxide (IGZO), which has better electron mobility. When the IGZO semiconductor is selected as the channel layer in the thin film transistor, a liquid etchant such as aluminic acid (Al acid) in general wet etching processes has a low etching selectivity between the IGZO and source/drain electrodes material (e.g. a multi-layered structure of Mo/Al/Mo). In other words, the etching process for patterning the source/drain electrodes also etches the IGZO channel layer. In the worst conditions, the IGZO channel layer is overly etched to be thinner than its predetermined thickness, such that the thin film transistor device cannot be normally operated due to its poor electrical properties.
Accordingly, a novel channel layer composition is called for, so that problems with the operation of the thin film transistor (due to the process of defining the source/drain electrodes simultaneously etching the IGZO channel layer) can be prevented.